Printing-blanket.



F. E. ELLIS.

PRINTING BLANKET.

APPLICATION FILED MAR.25| 1915' Patented Umh 26, 1915.

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EMNUK E. ELLIS, E REVERE, MASSACHUSETTS.

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To all whom it may concern:

Be it known that l, FRANK E. Ennis, of

of Massachusetts, have invented certain new and useful Improvements inPrmtinig- Blankets, of which the following is a spec cation.

The present invention relates to blankets for use in printing presses,and has for its object to provide a new and improved blanket especiallydesigned for lithographic or offset printing, that is that class ofprinting in which the design or text is taken from the printing plate orstone by the blanket and is transferred from the surface of the latterto the-paper or other substance being printed upon. Blankets adapted toperform this sort of work must have a smooth printing face of eventexture and must be resi1ient in uniform degree throughout 1ts ex-.

. tent.. If the blanket does not possess these qualities, it will causethe design to slur in being transferred to the paper or other substancebeing printed upon. Blankets for lithographic and offset printin haveheretofore been made largely 0 rubber by which I mean a compositioncontaining rubber gum with other ingredients, such as is commonly andordinarily understood by the term rubber, built up in a number of layerswith plies of friction fabric, the entire blanket having a smooth faceof rubber. Hitherto blankets of this sort have been of two classes: onewhich is known in the trade as the knife face or skin face blanket, hasfor the rubber constituent of its structure a number of sheets orlayers" formed by spreading a solution containing rubber andavulcanizing agent over the surface of fabric plies and adding enough ofsuch layers to bring the blanket to the required thickness. The othertype of blanket is constructed of rubber dough composed of rubber gumground up with litharge, talc, sulfur and other substances applied to anumber of plies of fabric and with a Suficient body on one face toprovide the printing surface, the whole being vulcanized into" a unitaryfabric and the face'belng ground off to make the blanket of uniformthickness.

Both of the above described forms of.

blanket are defective in one respect or another. The skin face blanket,while having a printing surface of the desired texture and finish forprinting, is yet very uneven as to thickness and stretches badly. lltcannot v @pe ciflcation of Letters Patent.

be ground on the printin face to. an even thickness, because grindlngdestroys the texture of the face and makes it unfit for print ng. Theother type of blanket is too hard and too little resilient to producethe best results in ofi'set printing. Both forms of blanket areexpensiveto make and are sub1ect to very rapid deterioration by thedestructive action of the oils contained in printers inks, which attackthe rubber printing face, causing it to blister and ren- Patented Wet.26, T915. hpplioafion med March 25, 1915. Serial No. 17,007.

improved blanket and in the method by which such blanket is produced.

In the drawings, Figure 1 is a sectional view enlarged of a blanketembodying my invention. Fig. 2 is a perspective view of a fragment ofsuch blanket showing the plies or layers thereof partially separated.

T will first describe the method of making the blanket and theingredients entering in its composition. '1 first provide a body layerof a cork'composition, such body layer being made by grinding a highgrade of selected cork into a condition of fineness resembling coarseflour or fine' meal, mixing the ground cork with an oxidizing oil, suchas rape seed oil, and spreading the composition of mixture smoothly overa ply of textile fabric by means of calendar rolls or in any othersuitable manner. The oxidizing oil will dry, and when dried the corkcomposition is soft and pliable.

In the drawings, a represents the cork layer and b the fabric layer onwhich the same is applied, as above described. As the cork compositionis spread upon the sheet of textile fabric while in the plasticcondition, it conforms to the texture of the fabric, entering to someextent in the spaces ing the particles of cork to one another wherebythose particles of cork which enter the meshes of the cloth effectuallylock the cork layer to the cloth.

The layer of cork with its fabric backing forms the bodyof the blanket,and after being thoroughly dried is prepared for union with the facelayer or ply of the blanket in the following manner: The surface of thecorklayer is first washed with a weak alkaline solution to remove theoil or oily coatmg upon such surface. The alkali which I prefer to usefor this purpose ispotash. I thenform a coating of rubber on this surface of the cork layer-by spreading evenly over the same a solution ofrubber gum. Such solution may have na htha or any other solvent as thevehicle or the rubber gum, and contains sulfur or any other ingredientor ingredients necessary or useful to effect vulcanization. I then layover the rubber coatedface of the cork layera sheet of textile fabricwhich has been, thoroughly stretched and previously coated with the samesolution. The coated sides of the cork and fabric of course are laidtogether. This layer of fabric is shown at c in the drawings, and theintermediate layer produced by the drying of'the dissolved rubbercomposition is indicated in Fig. 1 by the heavy line at d.

On the outer face of the fabric ply c I spread a layer 8 of rubbercomposition of the sort known in the art as rubber dough or greenrubber; the same being a mixture of rubber gumwith any of theingredients used I for other purposes to make a better blanket I providea final layer on the opposite side much less cost than those heretoforemade.

in rubbermanufacture for making the composition vulcanizable and givingit the desired color. v

A blanket composed of the parts above described is complete for somepurposes, of course after having been vulcanized, but

of the blanket from the face 6. This layer is a fabric ply f which isattached to the back of the fabric ply b by a coating 9 of vulcanizablerubber solution or cement in.

- the same manner that the ply 0 is united to the face of the corklayer. The whole blanket is then vulcanized by heat and pressure,preferably ina flat condition in a vulcanizlng press, wherein it is heldunder great ressure and subjected toa. temperature-o 325 degreesFahrenheit more or less for a period of from twenty-five to thirtyminutes, whereby the uncured layers of rub-.

'ber dough and dried cement are vulcanized.

After vulcanizing, the surface of the face layer e is made smooth andthe blanket brought-toexactly even thickness by grind-- ing or buffingthe outer surface of the layere sufiiciently to remove allirregularities.

I do not limit the steps of the method of to manufacture above describedto the particular order described in respect to applying the fabriclayer f, since such layer may be applied to the back of the layer 1)before the fabric a is applied to the face of the cork layer a; that is,the order in which the plies 0, f and e are applied to the body layermay be altered without departing from the invention. I

The blanket resulting from the process of manufacture abovedescribed'possesses a pliable and soft body which is not capable ofstretching, and moveover is reinforced so thoroughly on both sides bystrong sheets of fabric as to be prevented from breaking under tension.The blanket has a printing surface with the desired texture andsmoothness and has the necessary characteristic of uniform thickness. Myblanket has greater softness and resilience than the type of all rubberand fabric blanket, which is built up of frictionedv fabric pliesand alayer of' rubber dough, Whileit has the even thickness and theresistance to stretching of which the lack are serious defects in theskinthe stone becomes worn down as a result of repeated grindings toremove the design, and that with theordinary rubber blanket it isimpossible to use a stone after the same has become worn to a thicknessof about two and one-half inches. The greater, softness and resilienceof my blanket enables the stone to be used for a-much longer time, thatis after it has become reduced to a thickness much less than that aboveindicated.

Practically all the rubber in the blanket if is contained in the layere, which is only a small fraction of the thickness of the entireblanket, and as the cork and fabric parts of the blanket are much lessexpensive than rubber, the entire blanket can be made at I claim:

1. A printing blanket comprising a body layer of cork composition, arubber face layer in vulcanized union with one face of said body layer,and a sheet of textile fabric imited to the opposite face of said bodyayer.

2; Av printing blanket constructed of a face layer of vulcanized rubber,a body layer of a soft and pliable composition other than rubber,vulcanized to the face layer, and a backing layer of textile fabricunited to said body layer.

' 3. A printing blanket consisting of a body composed of a textilefabric ply and a sheet of granular cork and oxidize oil, bondedtogether, a second fabric ply bonded to the first fabric ly by a coatingof vulcanized rubber, a t ird fabric ply bonded to the of vulcanizedrubber, and a surface of vulcanized rubber united by vulcanization tothe outer side of said third ply.

i. A printing blanket particularly adapted for oflset printing having asmooth printing face and being of uniform thickness, and constructedmainly of resilient material other than rubber.

5. A printing blanket particularly adapted for ofl'set printingcomprising a body composed of a plurality of textile fabric plies and asheet of cork composition, with a surface layer having a smooth outerface.

6. A printing blanket particularly adapted for offset printingcomprising a body composed of a plurality of textile fabric plies and asheet of cork composition, with a surface layer having a smooth outerface, and being of such thickness as to make the entire blanketuniformly thick at all points.

7. A printing blanket particularly adapted for offset printingcomprising a body of soft, flexible, resilient material other thanrubber, a fabric backing layer securely bonded to said body, and a facelayer of a surface texture and smoothness suitable for a printingsurface.

8. A printing blanket particularly adapted for offset printingcomprising a body of soft, flexible, resilient material other thanrubber, a fabric backing layer securely bonded to said body, and arubber face layer of a surface texture and smoothness suitable for aprinting surface united by vulcanization to the body, the entire blanketbeing of uni.- form thickness at all points.

9. A printing blanket having a body of pulverized cork mingled with anoxidized vegetable oil, a textile fabric ply bound to one face of saidbody, a fabric ply bound to the opposite face of said body by vulcanizedrubber, and a rubber face layer vulcanized to the outer side of thesecond fabric ply.

10. The method of making a printing blanket which consists in providinga body layer of cork compositionhaving a fabric backing ply, making theface of said body layer adhesive to rubber, laying a fabric ply and aninterposed film of unvulcanized rubber upon the face of said body layer,placing a face layer of rubber composition on the outer side of thesecond named fabric ply, and vulcanizing the entire structure.

11. The method of making a printing blanket which consists in providinga body layer of cork composition mingled with an oxidized vegetable oilin dried condition and having a fabric backing ply, washing the face ofthe body layer with a solution capable of removing oil, laying a fabricply and an interposed film of rubber upon the face of said body layer,placing a face layer of rubber composition on the outer side of thesecond named fabric ply, and vulcaniz ing the entire structure.

12. The method of making a printing blanket which consists in providinga body layer of cork composition consisting of pulverized cork bondedwith an oxidized vegetable oil in dried condition and having a fabricbacking ply, washing the face of said body layer with an alkalinesolution to remove the oily coating of such face, laying a fabricply'and an interposed film of rubber upon the face of said body layer,placing a face layer of rubber composition on the outer side of thesecond named fabric ply, and vulcanizing the entire structure.

13. The. method of making a printing blanket which consists in taking abody consisting of a sheet of pulverized cork mingled with an oxidizableoil and a backing layer, in a substantially dried condition, removingthe oily coating from the face of said sheet by Washing the same with acaustic alkaline solution, attaching a fabric ply to the washed face ofthe body sheet with an interposed layer of vulcanizable rubber,spreading a layer of vulcanizable rubber composition on the face of saidfabric ply, and vulcanizing the entire structure.

14:. The method of making a printing blanket which consists in taking abody consisting of a sheet of pulverized cork mingled with an oxidizableoil and a backing layer, in substantially a dried condition, removingthe oily coating from the face of said sheet by washing the same with acaustic alkaline solution, attaching a fabric ply to the washed face ofthe body sheet with an in terposed layer of vulcanizable rubber,spreading a layer of vulcanizable rubber composition on the face of saidfabric ply, placing a fabric sheet with an interposed layer ofvulcanizable rubber on the back of said backing layer, and vulcanizingthe entire structure.

In testimony whereof I have affixed my signature.

FRANK E. ELLIS.

